/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 123
 * Date: 2023-06-02
 * Time: 10:30
 */
public class BinaryTree {

    static class TreeNode {
        public char val;
        public TreeNode left;//左孩子的引用
        public TreeNode right;//右孩子的引用

        public TreeNode(char val) {
            this.val = val;
        }
    }


    /**
     * 创建一棵二叉树 返回这棵树的根节点
     *
     * @return
     */
    public TreeNode createTree() {
        TreeNode A = new TreeNode('A') ;
        TreeNode B = new TreeNode('B') ;
        TreeNode C = new TreeNode('C') ;
        TreeNode D = new TreeNode('D') ;
        TreeNode E = new TreeNode('E') ;
        TreeNode F = new TreeNode('F') ;
        TreeNode G = new TreeNode('G') ;
        A.left = B ;
        A.right = C ;
        B.left = D ;
        B.right = E ;
        C.left = F ;
        F.left = G ;
        return A ;

    }

    // 前序遍历
    public void preOrder(TreeNode root) {
        if(root == null){
            return ;
        }
        System.out.print(root.val + "  ");
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    void inOrder(TreeNode root) {
        if(root == null){
            return ;
        }
        inOrder(root.left);
        System.out.print(root.val + "  ");
        inOrder(root.right);
    }

    // 后序遍历
    void postOrder(TreeNode root) {
      if(root == null){
          return ;
      }
      postOrder(root.left);
      postOrder(root.right);
        System.out.print(root.val + "  ");
    }

    public static int nodeSize;

    /**
     * 获取树中节点的个数：遍历思路
     */
    public void size(TreeNode root) {
        if(root == null){
            return ;
        }
        nodeSize ++ ;
        size(root.left) ;
        size(root.right) ;
    }

    /**
     * 获取节点的个数：子问题的思路
     *
     * @param root
     * @return
     */
    public int size2(TreeNode root) {

        if(root == null){
            return 0 ;
        }

        return size2(root.left) + size2(root.right) +1  ;
    }


    /*
     获取叶子节点的个数：遍历思路
     */
    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
        if(root == null){
            return ;
        }
        if(root.left == null && root.right == null){
            leafSize ++ ;
        }
        getLeafNodeCount1(root.left) ;
        getLeafNodeCount1(root.right) ;

    }

    /*
     获取叶子节点的个数：子问题
     */
    public int getLeafNodeCount2(TreeNode root) {
        if(root == null) {
            return 0;
        }

        if(root.left == null && root.right == null){
            return  1 ;
        }
        return getLeafNodeCount2(root.left) + getLeafNodeCount2(root.right)  ;

    }

    /*
    获取第K层节点的个数
     */
    public int getKLevelNodeCount(TreeNode root, int k) {
        if(root == null){
            return 0 ;
        }
        if(k == 1 ){
            return 1 ;
        }
       return getKLevelNodeCount(root.left , k -1 ) + getKLevelNodeCount(root.right , k -1 ) ;

    }

    /*
     获取二叉树的高度
     时间复杂度：O(N)
     */
    public int getHeight(TreeNode root) {
        if(root == null){
            return 0;
        }
     int leftHigh = getHeight(root.left) ;
     int rightHigh = getHeight(root.right) ;
     return leftHigh > rightHigh ? leftHigh + 1 : rightHigh + 1 ;
    }


    // 检测值为value的元素是否存在
  public  TreeNode find(TreeNode root, char val) {
        if(root == null ){
            return null ;
        }
        if(root.val == val){
            return root ;
        }

        TreeNode leftFind = find(root.left ,val) ;
        TreeNode rightFind = find(root.right ,val) ;
        if(leftFind != null){
            return leftFind ;
        }
        if(rightFind != null){
            return rightFind ;
        }
       return null ;
    }

    //层序遍历
    void levelOrder(TreeNode root) {
        if(root == null){
          return;
      }




    }


    // 判断一棵树是不是完全二叉树
    boolean isCompleteTree(TreeNode root) {


        return true;
    }
}